Abstract:
The Integrated Forest Study (IFS) was a project to evaluate the effects of atmospheric deposition on nutrient cycling in forest ecosystems. Deposition and nutrient cycling were monitored at 17 forested sites in the northwestern, northeastern, and southeastern United States and in Canada and Norway. The IFS was primarily funded by the Electric Power Research Institute (EPRI).

The Oak Ridge ... Loblolly Pine site was located on the U.S. Department of Energy Reservation, National Environmental Research Park, near Oak Ridge, Tennessee. The site consisted of loblolly pine with an understory of red maple, yellow poplar, black cherry, and dogwood. The ground cover consisted of extensive grass with patches of blackberry and honeysuckle. The site was located on an alluvial soil derived from shale on one of the upper terraces of the Clinch River.

Data collected included biomass and nutrient content of the overstory, understory, floor, and soils; atmospheric deposition, throughfall, stemflow, and soil solution fluxes for major ions; organic matter and nutrient fluxes; and atmospheric concentrations of ions from wet and dry deposition.

Data on atmospheric chemistry and wet deposition were collected on an event basis throughout the year. Nutrient cycling data were collected at or adjacent to the study area. Wet deposition of all major ions was collected with automatic collectors. Atmospheric chemistry measurements were made on an event basis using samplers situated on 5-10 m towers above the forest canopy. These measurements included: (1) major ions in aerosols collected on teflon filters and in coarse particles dry-deposited on inert plates; (2) sulfur dioxide (SO2) and nitric acid (HNO3); and (3) ozone (O3) sampled continuously with UV absorption detectors. Meteorological data were also collected continuously from the towers including mean temperature, solar radiation, relative humidity, wind direction and wind speed, and precipitation amount.

The seasonal and annual input of ions in rain, throughfall, and stemflow were calculated from the product of precipitation-weighted mean ion concentrations in each solution and the hydrologic flux. Dry deposition was calculated from the product of event mean air concentrations and appropriate deposition velocities. Organic matter, nitrogen (N), phosphorous (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg) contents of vegetation, forest, and floor, and soils and nutrient fluxes via litterfall, throughfall, and soil solution were estimated. Aboveground vegetation biomass was estimated from regression equations. Forest floor mass was determined by random destructive sampling and soil nutrient content was estimated. Litterfall was collected in traps and analyzed for nutrient content. Bulk throughfall was collected and analyzed and stemflow was collected using collar methods. Soil solutions were collected by means of tension lysimeters.